1. Field
The present disclosure relates to new arylpyridinone compounds and compositions, and their application as pharmaceuticals for the treatment of disease. Methods of inhibition of ITK activity in a human or animal subject are also provided for the treatment diseases such as those caused by inflammation.
2. Description of Related Art
The Tec (tyrosine kinase expressed in hepatocellular carcinoma) family of tyrosine kinases (TFTK) consists of five family members: Tec, BTK (Bruton's tyrosine kinase), BMX (bone marrow kinase on the X chromosome also known as ETK), RLK (resting lymphocyte kinase also known as TXK) and ITK (interleukin-2 inducible T cell kdsinase, also known as EMT and TSK). These kinases are central to the regulation of hematopoietic cell biology and more specifically the development and activity of lymphocytes and myeloid cells (Horwood et al. (2012) Int. Rev. Immunol. 31, 87-103; Boucheron et al. (2012) Int. Rev. Immunol. 31, 133-154; Koprulu et al. (2009) Crit. Rev. Immunol. 29, 317-333). The TFTK have structural similarities to other non-receptor tyrosine kinases while exhibiting some family specific motifs resulting in a diversity of domain structures associated with complex localization, scaffolding and activation mechanisms. Generally, TFTK contain an amino terminal plekstrin homology domain (PH domain) involved in lipid interactions and membrane targeting followed by a BTK homology domain (BH) that binds Zn2+ and an SH3 domain generally involved in proline rich domain binding. A phosphotyrosine binding SH2 domain and a carboxy terminal ATP binding kinase domain complete the TFTK structure (Mano, et al. (1999) Cytokine Growth Factor Rev. 10, 267-280). TFTK expression is generally limited to hematopoietic lineage cells with the exception of ETK and TEC that are expressed in the liver and endothelial cells, respectively (Smith, et al. (2011) Bioessays 23, 436-446). BMX is expressed in monocytes, granulocytes and cardiac endothelium while BTK is expressed in B cells and mast cells but not plasma cells and T cells. TEC, RLK and ITK are all expressed in T cells. To date the TFTK with the most clear biological role in T cells is ITK.
Antigen/MHC dependent activation of the T cell receptor (TCR) has been shown to transduce its signal through ITK. TCR stimulation results in the activation of the kinase LCK and subsequent phosphorylation of the immunoreceptor tyrosine-based activation motifs (ITAMs) on CD3 inducing the binding and activation of the kinase ZAP70. In turn, ZAP70 phosphorylates the adaptor proteins LAT and SLP-76, which together with LCK and other proteins forms a hetermultimeric signaling complex that activates PI3K and generates PIP3 on the plasma membrane. ITK binds to this signaling complex via SH2 and SH3 domains and to PIP3 through its PH domain, resulting in LCK dependent phosphorylation of ITK Y511 and subsequent ITK autophosphorylation of Y180. Activated ITK phosphorylates PLCγ1 that, once activated, hydrolyzes PIP2 to the second messengers IP3 and DAG. The cellular consequences of these sequelae of events include calcium mobilization and flux, PKC and MEK/ERK pathway activation, and transcriptional activation via APi, NFκactiv NFAT. As a critical enzyme in the TCR activation pathway ITK impacts T cell function in a number of ways including positive and negative selection, cellular differentiation, and cytokine production and release (Takesono, et al. (2002) J. Cell Science 115, 3039-3048; August, et al. (2012) Int. Rev. Immunol. 31, 155-165; Andreotti, et al. (2010) Cold Spring Harb. Perspect. Biol. 2, a002287 1-21).
The role of ITK in T cell function has been delineated through genetic knockdown/kinase inactivation of the ITK gene in rodents and through characterizing human ITK mutant individuals. Mice with a null mutation of the itk gene expressed a decreased number of mature T cells and a block in thymocyte development as well as a decreased TCR driven T cell proliferative response. Interestingly IL2 and CD28 signaling as well as PMA/ionomycin driven responses remained unchanged, suggesting that the ITK response is membrane proximal and stimuli specific (Liao et al. (1995) Immunity 3, 757-769). It appears that ITK is responsible for amplification of TCR signaling versus an ‘on/off’ switch, as dual knockdown of the T cell expressing TFTK, ITK and RLK in mice produce a more complete TCR inactivation phenotype compared with ITK genetic deletion alone (Schaeffer et al. (1999) Science 284, 638-641). In contrast to the modulatory effect that ITK appears to have on naïve T cell activation, it plays a more significant role in T helper cell differentiation. Several studies in ITK deficient mice have demonstrated a reduction in the Th2 protective response to parasitic infection (Fowell et al. (1999) Immunity 11, 399-409; Schaeffer et al. (2001) Nat. Immunol. 2, 1183-1188). This reduced Th2 response was linked to a decrease in concentrations of Th2 cytokines IL4, IL5, IL13 and IL10 (Schaeffer et al. (2001) Nat. Immunol. 2, 1183-1188) and to a reduction in RLK expression. In contrast to the ITK requirement for mounting Th2 driven responses, its impact on Th1 responses is modest. For example, IFNg production in ITK knockout cells is partially inhibited while the double ITK/RLK knockout has a more severe phenotype (Fowell et al. (1999) Immunity 11, 399-409; Schaeffer et al. (2001) Nat. Immunol. 2, 1183-1188; Miller et al. (2004) Immunity 21, 67-80). Evaluation of Th17 T helper cells in ITK knockout in vivo and in vitro studies demonstrated a reduction of IL17A mRNA and protein while having little impact on IL17F (Gomez-Rodriguez et al. (2009) Immunity, 31, 587-597). The role of ITK in cytotoxic CD8+ T cells was investigated using ITK knockout mice. Stimulation of CD8+ T cells deficient in ITK results in a reduction in activation of PLCg1, ERK and p38 MAPK and loss of Ca2+ response resulting in decreased proliferative response and effector cytokine production (IL2, IL4 and IFNg) while not impacting cytolytic capacity of these cells (Atherly et al. (2006) J. Immunol. 176, 1571-1581). In addition to the defects observed in CD4+ and CD8+ T cells, natural killer T cell development and TCR stimulated response is reduced in ITK knockout cells and animals (Au-Yueng et al. (2007) J. Immunol. 179, 111-119; Felices et al. (2008) J. Immunol. 180, 3007-3018).
Rodent genetic knockout studies reflect the impact of enzyme expression, not necessarily its catalytic activity, on biological responses. As ITK, through its multiple domain structure, has a role in scaffolding, in addition to its catalytic role. It is important to delineate the impact of blocking each of these functions on cellular biology. Kinase activity-independent ITK activities include recruitment of the guanine nucleotide exchange factor VAV to the cell membrane associated with actin polymerization (PH and SH2 domain dependent) (Atherly et al. (2006) J. Immunol. 176, 1571-1581), antigen receptor stimulation, and receptor activation of SRF (Dombroski et al. (2005) J. Immunol., 174, 1385-1392). However, ITK knockout mice expressing an ITK kinase domain deleted transgene demonstrated that the kinase domain is essential for induction of a normal Th2 response (von Bonin et al. (2011) Exp. Dermatol. 20, 41-47).
The relationship between ITK expression and activity and human disease has recently been documented in studies characterizing individuals exhibiting mutations in the gene encoding this protein and or correlation between expression and disease. The ITK gene was found to be elevated in peripheral blood T cells from patients with moderate to severe atopic dermatitis, a Th2 driven chronic inflammatory skin disease (Hao et al. (2006) FEBS Letts., 580, 2691-2697). An investigation of disease-associated single nucleotide polymorphisms (SNP) in seasonal allergic rhinitis identified ITK as a significant risk factor (Matsumoto et al. (2002) Int. Arch. Allergy Immunol. 129, 327-340). A human primary immunodeficiency was uncovered in siblings that died from immune dysregulation resulting in lymphoproliferation following Epstein Barr Virus (EBV) infection. This disorder was linked to a missense (R335W) mutation in the SH2 domain of ITK resulting in structural instability and reduced steady state levels of the enzyme (Felices et al. (2008) J. Immunol., 180, 3007-3018). The finding was confirmed and extended in studies that identified three patients harboring a C1764G nonsense mutation in ITK resulting in a premature stop codon and reduced expression and/or activity of the protein. These patients presented with EBV-positive Hodgkins Lymphoma (Huck et al. (2009) J. Clin. Invest. 119, 1350-1358). These two reports suggest that mutational disruption of the ITK gene in humans results in an autosomal recessive lymphoproliferative disorder and identifies this kinase as a critical modulator in T cell biology.
In addition to the human genetic data summarized above, animal models support ITK as a therapeutic target for autoimmune and inflammatory disease. ITK knockout mice demonstrate reduced airway hypersensitivity and inflammation in models of allergic asthma (Stepensky et al. (2011) Haematologica, 96, 472-476; Mueller et al. (2003) J. Immunol., 170, 5056-5063; Ferrara et al. (2004) Pulm. Pharmacol. Ther. 17, 301-308). In a murine model of atopic dermatitis, ITK deficient mice do not develop inflammation while ITK inhibition reduces the response in wild type mice (Ferrara et al. (2006) J. Allerg. Clin. Immunol. 117, 780-786). The ITK dependent regulation of TCR dependent Ca2+ mobilization and transcription factor induction makes it a critical factor in protecting against Influenza A and HIV infection and viral replication. ITK inhibitors have been shown to alter HIV replication at multiple stages and have the potential as effective HIV therapeutics (Sahu et al. (2008) J. Immunol. 180, 3833-3838).
From an oncology perspective, studies have demonstrated that ITK inhibitors selectively target the killing of acute lymphblastic T-cell leukemia and cutaneous T-cell lymphoma while normal T cells are minimally impacted (Readinger et al. (2008) Proc. Nat. Acad. Sci. USA, 105, 6684-6689). ITK is highly expressed in transformed T-cell lines relative to normal T cells and other cancer cell lines. The impact of ITK inhibition on T cell tumors was confirmed in mouse xenograph models. Cancer evasion of the immune system as a result of tumor antigen tolerance induction versus priming is critical for tumor survival. Tumors that develop a microenvironment that induces T cell unresponsiveness demonstrate altered T cell gene expression suggesting skewing to the Th2 phenotype. ITK inhibition will favor Th1 differentiation and could be used to enhance cancer immunotherapy (Gao et al. (2012) Mol. Pharmacol., 82, 938-947; Horna et al. (2007) Curr. Cancer Drug Targ. 7, 41-53).
Compounds useful as BTK inhibitors for the treatment of inflammation and immune disorders are reported in WO 2012031004 (pub. 8 Mar. 2012). Compounds described therein include arylpyridinones substituted with amino substituents.
Compounds useful as cannabinoid 2-type receptor inhibitors are reported in WO 2002053543 (pub. 11 Jul. 2002). Compounds described therein include arylpyridinones substituted with amido substituents.
Compounds useful as SYK inhibitors for the treatment of inflammation and immune disorders are reported in EP 2489663 (pub. 22 Aug. 2012). Compounds described therein include N-pyrazinyl-indoles and N-pyrazinyl-indole pyridinones substituted with amino substituents.
Compounds useful as thrombin inhibitors for the treatment of blood and coagulation disorders are reported in WO 2000026211 (pub. 11 May 2000). Compounds described therein include N-substituted pyrazinones substituted with amino substituents.